The secondary locking mechanisms to prevent the relative rotation and loosening of various separable connectors or fasteners have been developed over a long period of time, and different types of mechanisms have been created for various applications. In aerospace applications, anti-rotation features are important and external secondary locking mechanisms are widely used in different structures. In an assembly of rotating equipment such as gas turbine engine fans, for example, there are occasions where blind assembly of bolts would be required. In such situations, the head of the bolt cannot be reached at the time that components to be joined are installed, when applying a nut, or when tightening a nut. Various clips and retaining means are known to retain a bolt at such time. In other situations, external secondary locking mechanisms are used for locking connectors that join tubes, hoses and wiring together or to an accessory unit. The requirements for aerospace applications are particularly stringent, in particular, for use on engines, hydraulic systems, fuel systems and electrical cable connectors. The current and most common means for secondary locking of aerospace connectors or fasteners are lock wires and safety wires which require special features to be incorporated in the connectors or fasteners. Other means comprise crimp nuts, fibre nuts and tab washers. These external locking devices may permit some small relative rotation of the connectors or fasteners, and usually are destroyed or rendered non-reusable in aerospace applications, once unlocked to open the connectors or unfasten the fasteners.
With high speed rotating equipment, high stresses are formed and notches, scratches or plastic deformation forms stress concentrations. Any such stress concentration can cause failure during the operation of the apparatus. It is therefore desirable that any external secondary locking mechanism not require a basic component design having a substantial stress concentration. Lightweight is also important in such high-speed rotating equipment and, accordingly, a lightweight, simply construed secondary locking mechanism is desired. Efforts have been made to improve external secondary locking mechanisms in aerospace applications and one example is shown in U.S. Pat. No. 5,350,201, entitled SEPARABLE CONNECTOR EXTERNAL CAPTURE DEVICE and issued to K. K. Bynum on Sep. 27, 1994. Bynum describes an external capture device having two co-axial spring clips sized to tightly grip the external surfaces of the separable connector to be secured. Each clip is a semi-circular spring band and serrated in form and joined by an axial bar. In another example, Dimmick III et al. describe in U.S. Pat. No. 4,887,949, which is entitled BOLT RETENTION APPARATUS and issued on Dec. 19, 1989, a retention clip co-operating with a bolt and a flange through which the bolt passes to retain the bolt during blind assembly.